Ashless lubricating oil detergents

ABSTRACT

ASHLESS LUBRICATING OIL DETERGENTS ARE PROVIDED BY THE REACTION PRODUCT OF: (A) A CARBOXYLIC ACID OR ACID ANHYDRIDE CONTAINING ADDITION COPOLYMER HAVING AT LEAST TWO ACID OR ANHYDRIDE GROUPS, OPTIONALLY COMPOSED IN PART OF MONOMERIC CARBOXYLIC ACID OR ANHYDRIDE, (B) AN AMINE, AND (C) AN AMINOPHENL.

United States Patent U.S. Cl. 260-785 4 Claims ABSTRACT OF THE DISCLOSURE Ashless lubricating oil detergents are provided by the reaction product of:

(A) a carboxylic acid or acid anhydride containing addition copolymer having at least two acid or anhydride groups, optionally composed in part of monomeric carboxylic acid or anhydride,

(B) an amine, and

(C) an aminophenol.

This application is a division of application Ser. No. 734,210, filed June 4, 1968 and now U.S. Pat. 3,476,686, Nov. 4, 1969, which application is a continuation-in-part of application Ser. No. 487,624, filed Sept. 15, 1965, and now abandoned.

The present invention is directed to novel materials useful, for instance, as additives for lubricating oils. More specifically the invention concerns the reaction products of a carboxylic acid copolymer, an aminophenol, and an amine, and the alkaline metal salts of the reaction products which materials find use as lubricating oil detergents and antioxidants. If desired the carboxylic acid component can be composed in part of monomeric carboxylic acid or anhydride.

The use of metallic detergents in internal combustion engine lubricating oil compositions is Well known, particularly ultility for these detergents being found in lubricating oil compositions which are subjected to heavy duty service resulting in the oxidation of the oil with the resultant formation of sludge and varnish. Although these detergents such as metallic petroleum sulfonates have been very useful in maintaining sludge and varnish suspended in the oil they have the disadvantage of being themselves subject to break-down and deterioration resulting in the formation of a metallic ash which accumulates in the combustion chamber of the internal engine.

Another drawback of many metallic detergents is that they lack suflicient basicity to effectively counteract the deleterious acidic materials commonly found in lubricating oils. Nor have these metallic detergents proven effective in dispersing the blow-by contamination of the lubricating oil when the engine is operated in light service and at low operating temperatures. When the engine is cold the cylinder walls act as a condenser for the fuel vapors and combustion products in the cylinder. These contaminants Wash past or blow-by the piston rings into the crankcase wherein they tend to emulsify and coagulate causing insoluble sludge deposits which the usual metallic detergents are unable to redisperse. To overcome these blow-by contaminants and to disperse the sludge 'depositsin the crankcase, attempts have been made to provide ashless dispersants which will prove effective at the low operating temperatures found in light service internal combustion engines.

It has now been found that the base oil-soluble reaction product of a copolymeric carboxylic acid, an aminophenol and an amine when added to a base oil of lubricating viscosity in small amounts, provides the oil with excellent dispersant and antioxidant properties. The reaction product can also be used as an alkaline metal salt and can include monomeric carboxylic acid, for instance, reacted as an anhydride.

The sequence in which the reactants can be combined to afford the oil-soluble additives of the present invention may be varied depending upon the products which are being prepared. Regardless of the sequence of reaction and reaction conditions, however, about 0.1 to 2 moles, preferably about 0.2 to 1 mole, of total amine per average reactive carboxylic acid group (including anhydride group as one such carboxyl group) is generally reacted per mole of reactive acid group, and at least about 0.2 mole, preferably up to about 2 moles, of the aminophenol per average basic nitrogen atom present in a mole of amine reactant, is reacted. Advantageously, the aminophenol is present in an amount of about 0.2 to 1 mole per average moles of basic nitrogen atom in the amine.

The three major reactants which can be employed to form the reaction products of the reaction will be described under separate headings.

THE COPOLYMERIC CARBOXYLIC ACID REACTANT The copolymeric carboxylic acids of the present invention may be the various materials having a polymeric backbone, preferably hydrocarbon and having at least two carboxylic acid or acid anhydride groups. These polymeric materials include, for instance, the copolymers of ethylenically unsaturated carboxylic acids and anhydrides of 3 to 15 carbon atoms; and noncarboxylic addition polymerizable vinyl compounds of 2 to 12 carbon atoms such as for example ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, dodecylene, methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, styrene or other polymerizable vinyl compounds; as well as copolymers of more than one of either the vinyl compounds or the unsaturated acids or both. Preferred examples of these materials are styrene-maleic anhydride copolymers, alkylvinyl ether-maleic anhydride copolymers, ethylene-maleic anhydride copolymers, alphaolefin-maleic anhydride copolymers, etc. Other preferred copolymeric carboxylic acid anhydride products such as copolymers derived from the polymerization of styrene and acrylic acid; butadiene and acrylic acid; butadiene and methacrylic acid; styrene, alpha-olefin and maleic anhydride; styrene, alpha-olefin and ocrylic acid, etc., can be employed to prepare additives of the present invention. The average molecular weights of the copolymeric carboxylic acids may often vary from about 200 to 40,000, preferably about 400 to 10,000.

Particularly preferred acid reactants are the copolymer resins of the above-described vinyl compounds and maleic anhydride, for instance, styrene-maleic anhydride resins. Usually a mole ratio of vinyl compound to maleic anhydride is of about 1 to 4:1, preferably 1 to 3:1 is employed to prepare the copolymer. These copolymer resins may contain repeating vinyl compound-maleic anhydride units and preferably have an average molecular weight of about 400 up to about 40,000 or more, preferably about 400 to 3,000. The melting points of the lower molecular weight copolymers will generally range from about 80 to 300 C. as determined by the Fisher-Johns Melting Point Apparatus. The determination of average molecular weight as used herein is made by the Thermoelectric Differential Vapor Pressure Lowering Method on a Microlab Oamometer.

The copolymer carboxylic acid reactant can be composed in part of monomeric carboxylic acid, for instance, the latter material may be as much as 80 molar percent of the total carboxylic acid reactant. When the monomeric acid is used it may be a minor molar amount of the total carboxylic acid reactant and is preferably at least about 5 molar percent of the total when employed. The monomeric carboxylic acid of the present invention may be a monoor polycarboxylic acid including the corresponding acid anhydrides, esters or acid halides of the carboxylic acids. The acid can be straight chain or branched, saturated or unsaturated, aliphatic (including cycloaliphatic), aromatic or heterocyclic. The monomeric carboxylic acids include, for instance, the monocarboxylic and polycarboxylic acids and their anhydrides, containing at least about 2, and often up to about 26 or more, carbon atoms. The preferred monomeric carboxylic acids are the aliphatic monoand dicarboxylic or alkanoic acids and anhydrides of 2 to about 21 carbon atoms. Illustrative of suitable monomeric carboxylic acids and anhydrides are the fatty acids, preferably of about 8 to 21 carbon atoms such as lauric acid, stearic acid, palmitic acid, oleic acid and the like. Examples of suitable monomeric polycarboxylic acids are succinic acid, alkyl or alkenyl succinic acids wherein the alkyl or alkenyl group contains say from 1 to about 200 carbon atoms or more, trimellitic acid, pyromellitic acid, naphthalene 2,6-dicarboxylic acid, naphthoic anhydrides, phthalic anhydride, isophthalic acid, maleic anhydride, itaconic acid, etc.

AMINE REACTANT The amine component of the reaction product of the invention can be either a monoamine or a polyamine or both, for instance, each in an amount of at least about 0.05 mole per mole of reactive carboxylic acid group of the carboxylic acid reactant.

The monoamine reactant of the invention includes those having the formula:

wherein R is a monovalent hydrocarbon radical, preferably alkyl, including cycloalkyl, of up to about 100 or more carbon atoms, preferably about 5 to 25 carbon atoms, and R is R or hydrogen. Advantageously, at least one R has at least 5 carbon atoms, for instance about 12 to 20 carbon atoms. R can be straight or branched chain, saturated or unsaturated, aliphatic or aromatic, and is preferably saturated. The preferred monoamines are the primary monoamines. Examples of suitable monoamines are amyl amine, 2-ethylhexyl amine, n-octyl amine, decyl amine, octadecyl amine, lauryl amine, stearyl amine, N-methylstearyl amine, N-ethyl octadecyl amine, Z-phenyl decyl amine, and the like or mixtures thereof. The monoamine can also be substituted with groups which do not interfere with the reaction of the amino group of the amine with the acid moiety of the carboxylic acid component and do not otherwise unduly deleteriously affect the desired properties of the final reaction product.

Suitable polyamines of the invention include those represented by the formula:

N- RNH wherein n is a number of at least I, commonly 2 to about R is an alkylene radical of 2 to about 25 carbon atoms, preferably 2 to 19 carbon atoms, and R is selected from H and a hydrocarbon radical, such as alkyl, including cycloalkyl, of 1 to about 30 carbon atoms, preferably of 1 to about 7 carbon atoms. Both R and R can be substituted with non-deleterious groups.

These polyamines include monoalkylene diamines, dialkylaminoalkylamines and the polyalkylenepolyamines. Illustrative of suitable monoalkylene diamines are ethylene diamine, propylene diamine, butylene diamine, octylene diamine, etc. Examples of suitable dialkylaminoalkyl amines are dimethylaminomethylamine, dimethylaminoethylamine, dimethylaminopropylamine, dimethylaminobutylamine, diethylaminopropylamine, methylpropylaminoamylamine, propylbutylaminoethylamine, etc. Nonlimiting examples of the polyalkylenepolyamine reactants are diethylenetriamine; triethylenetetramine; tetraethylenepentamine; etc.

THE AMINOPHENOL Amino-phenols such as p-aminophenols, are incorporated into the reaction products of the present invention by reaction with one or more of the carboxylic acid or anhydride groups of the carboxylic acid reactant of the invention to form imide or amide groups. Suitable aminophenol derivatives include, for instance, the following types:

wherein R is selected from hydrogen and hydrocarbon groups such as alkyl, aryl, alkenyl and the like, and n is an integer of 1 to 4. The R groups can be the same or different. The present invention also contemplates use as the amino phenol component, aromatic derivatives other than phenyl derivatives as, for instance, aminonaphthols and similar derivatives of biphenyl, terphenyl, phenanthrene, anthracene, etc. The total carbon atoms in the aminophenol may often range from 6 to about 24 or 30 or more.

As discussed above the sequence of reaction can vary depending upon the particular rectants employed. For instance, when preparing reaction products from styrenemaleic anhydride resins, the resin (i.e., the acid reactant) may first be reacted with the amine component and the resulting product then reacted directly with the aminophenol, such as p-aminophenol. Reaction of the styrenemaleic anhydride copolymer and the amine may be conducted at a reaction temperature of about to 350 0, preferably about to 280 C. Reaction of the resulting product with aminophenol is usually conducted at a temperature of about 125 to 350 C., preferably about 190 to 280 C. Both of the reactions are conveniently carried out at atmospheric pressure but subor super-atmospheric pressure can be employed, if desired. The reaction may be carried out in bulk or in the presence of a mutual solvent for the reactant.

In many instances, more than one carboxylic acid or carboxylic acid anhydride may be reacted with one or more of the amines of the invention. Also, the reactants can be reacted simultaneously, for instance, at about 125 to 350 C., preferably about 190 to 280 C. Various orders of addition of the reactants can be used, for example, a portion of the amine such as the monoamine can be reacted with the carboxylic acid and aminophenol and then the resulting intermediate reacted with the polyamine.

The following is illustrative of one of the reactions that may be employed to produce the products of the present invention.

Styrene-maleic anhydride resin-l-p-aminophenol with condensation product of an alkenylsuccinic anhydridepolyamine.

The condensation products of this invention are characterized as either having at least one reactive phenolic hydroxy group which remains unsubstituted or is replaced with an alkalinemetal. The oil-soluble alkaline metal salts, particularly the calcium salts, are effective for imparting thermal and oxidative stability to mineral oils. By alkaline metal is meant the alkali metals such as sodium, potassiume and lithium and the alkaline earth metals such as calcium, barium and strontium. The alkaline salts can be prepared by neutralization of the condensation product with a basic compound of the alkaline metal as, for instance, the hydroxides, oxides, carbonates and the like or by neutralization With a'metal oxide or hydroxide followedby preparation of the alkaline metal salt by metathesis. Preferably When carrying out the neutralization of the condensation product, additional mineral oil of the type employed in preparing a mineral oil concentrate is added to the reaction mixture together with the basic compound and a small amount of water to facilitate the neutralization. Greater than stoichiometric equivalents of the alkaline earth metals can be used, if desired, to given basic salts.

The base oil into which the reaction product of the invention is incorporated can be of lubricating viscosity and can be a mineral oil or a synthetic oil. The mineral lubricating oils can be, for instance, solvent extracted or solvent refined oils obtained in accordance with conventional methods of solvent refining lubricating oils. Frequently, the viscosity of these mineral oils will be about to 250 SUS at 210 F. The mineral base oil may, for example, be derived from paraflinic, naphthenic, asphaltic or mixed base petroleum crudes, and if desired, a blend of solventtreated Mid-Continent neutrals and Mid-Continent bright stocks may be employed.

Synthetic oils to which the reaction product may be added include ester-based synthetic oil of lubricating viscosity which consists essentially of carbon, hydrogen and oxygen, e.g., di-3-ethylhexyl sebacate. Various of these lubricating materials have been described in the literature and generally their viscosity ranges from the light to heavy oils, e.g., about 50 SUS at 100 F. to 250 SUS at 210 F., and preferably to 150 SUS at 210 F. These esters are of improved thermal stability, low acid number and high flash and fire points. The complex esters, diesters, monoesters and polyesters may be used alone or to achieve the most desirable viscosity characteristics, complex esters,

CH3 CH 0 CH3 m 3 30 diesters and polyesters may be blended with each other or With naturally-occurring esters like castor oil to produce lubricating compositions of Wide viscosity ranges which can be tailor-made to meet various specifications. This blending is performed, for example, by stirring together a quantity of diester and complex ester at an elevated tem- 2,703,811, 2,705,724 and 2,723,286. Generally, the synthetic base oils consist essentially of carbon, hydrogen and oxygen, i.e., the essential nuclear chemical structure is formed by these elements alone. However, these oils may be substituted with other elements such as halogens, e.g., chlorine and fluorine. Some representative components of ester lubricants are ethyl palmitate, ethyl stearate, di-(Z-ethyhexyl) sebacate, ethylene glycol dilaurate, di-(Z- ethylhexyl) phthalate, di-(1,3-methylbutyl) adipate, di-(2- ethylbutyl) adipate, di-(l-ethylpropyl) adipate, diethyl oxylate, glycerol tri-n-acetate, di-cyclohexyl adipate, di- (undecyl) sebacate, tetraethylene glycol di-(Z-ethylenehexoate), di-cellosolve phthalate, butyl phthallyl butyl glycolate, di-n-hexyl fumarate polymer, dibenzyl sebacate and diethylene glycol bis-(Z-n-butoxy ethyl carbonate). 2-ethyl-hexyl-adipate neopentyl glyoly-adipate-Z-ethylhexyl, is a representative complex ester.

The compositions of this invention incorporate a small, minor amount of the above-described reaction product sufiicient to provide the base oil of lubricating viscosity, which is the major portion of the compositions, with improved detergent and antioxidant properties. This amount is generally about 0.1 to 10 weight percent or more depending on the particular base oil used and its application. The preferred concentration is about 0.2 to 5%.

Materials normally incorporated in lubricating oils and greases to impart special characteristics can be added to the composition of this invention. These include corrosion inhibitors, extreme pressure agents, antiWear agents, etc. The amount of additives included in the composition usually ranges from about 0.01 Weight percent up to about 20 or more weight percent, and in general they can be employed in any amounts desired as long as the composition is not unduly deleteriously affected.

The following examples are included to further illustrate the present invention.

7 EXAMPLE I Preparation of mixed octadecylamine, diethylaminopropyl amine and p-aminophenol condensation products with styrene-maleic anhydride resins Into a 1-liter resin kettle, equipped with a stirrer, reflux condenser (and Dean Stark trap), thermometer, nitrogen inlet tube, was placed 202 gms. of a 600700 molecular weight styrene-maleic anhydride copolymer (of 1:1 styrene to maleic anhydride mole ratio), 243 grams of octadecylamine, 10.9 gms. of p-aminophenol and 469 gms. of 95 VI mineral lubricating oil. The mixture was heated to 220 C. until the water of reaction began to collect in the Dean Stark trap. The diethylaminopropyl amine (13 gms., 0.1 mole) was added dropwise to the mixture and the reaction continued for a period of 3 hours at 220 C. The resulting product was a dark brown, viscous liquid, which was completely soluble in paraflinic lubricating oils and most organic solvents. The properties of this additive displayed in a lubricating oil having a VI of 95 and a viscosity SUS at 100 F. of 150 were as follows:

The above additives, at 1, 2 and 3 percent concentrations showed excellent properties in the tests for detergency. The additive also showed oxidation inhibiting properties.

EXAMPLE II Preparation of octadecylamine, p-aminophenol derivatives of styrene-maleic anhydride resin Into a 1-liter resin kettle, equipped as previously described, was placed 395 gms. of the lubricating oil of Example I, 202 gms. (1 mole) of styrene-maleic anhydride copolymer resin (approximately 600-700 molecular weight and a mole ratio of styrene: maleic anhydride of 1:1), 182 gms. (0.67 mole) of octadecylamine and 10.9 gms. (0.1 mole) of para-aminophenol. The mixture was heated at a temperature of 220230 C. for a period of 2 hours, during which time the theoretical amount of water was collected. The product was an amber viscous liquid, which was completely soluble in lubricating oils and most organic solvents. The properties displayed by this product in the lubricating oil of Example I are shown below:

Viscosity Pgur KV 100 KV 120 index F Percent concentration:

The above resin showed good properties as in ashless detergent and dispersant when formulated in lubricating oils. Lubricating oils compositions containing this additive also showed improved oxidation resistance.

EXAMPLE HI Preparation of reaction product of styrene-maleic anhydride resin, diethylene triamine, polybutenyl succinic anhydride and p-aminophenol 8 gent-inhibitor in lubricating oils. The additive also showed good oxidation inhibiting properties.

In addition to the alkaline metal salts described above, other useful salts of the reaction product of the invention which can be prepared are the nickel, zinc, aluminum and other metals.

We claim:

1. The oil-soluble reaction product obtained by reaction at about 125 to 350 C. of:

(A) carboxylic acid consisting essentially of copolymer of an addition polymerizable, noncarboxylic vinyl compound of 2 to 12 carbon atoms selected from the group consisting of styrene, alkyl-vinyl ethers and alpha-olefins and mono-ethylenically unsaturated carboxylic acid or anhydride of 3 to 15 carbon atoms and at least two carboxylic acid groups, said copolymer having a molecular weight of about 200 to 40,000, and 0 to about mole percent of monomeric carboxylic acid of at least about 2 carbon atoms,

(B) amine selected from the group consisting of:

(l) monoamine having the formula:

wherein R is alkyl of about 5 to 25 carbon atoms, and R is selected from the group consisting of hydrogen and R, and

(2) polyamine having the formula:

wherein n is an integer of 1 to 10; R is alkylene of 2 to 25 carbon atoms and R is selected from the group consisting of H and hydrocarbon of l to about 30 carbon atoms, and

(C) aminophenol having from 6 to about 30 carbon atoms; the mole ratio of (B) to (A) being about 0.1 to 2 moles of (B) per reactive carboxylic acid group per mole of (A), and said reactant (C) being present in an amount of about 0.2 to 2 moles per mole of basic nitrogen per mole of reactant (B).

2. The oil-soluble reaction product obtained by reaction at about to 350 C. of:

(A) copolymer of styrene and maleic anhydride having a mole ratio of styrene to maleic anhydride of about 1 to 3:1 and a molecular weight of about 400 to 3,000,

(B) amine selected from the group consisting of:

(l) monoamine having the formula:

wherein R is alkyl of 5 to 25 carbon atoms and R is selected from the group consisting of hydrogen and R, and

(2) polyamine having the formula:

wherein n is an integer of 2 to 10; R is alkylene of 2 to 7 carbon atoms and R is selected from the group consisting of hydrogen and alkyl of 1 to about 7 carbon atoms, and (C) aminophenol having from 6 to about 24 carbon atoms: the mole ratio of (B) to (A) being about 0.1 to 2 moles of (B) per reactive carboxylic acid group per mole of (A) and said reactant (C) being present in an amount of about 0.2 to 2 moles per basic nitrogen per mole of reactant (B).

9 3. The oil-soluble reaction product obtained by reaction at about 125 to 350 C.:

(A) copolymer of styrene and rnaleic anhydride having a mole ratio of styrene to maleic anhydride of about 1 to 3:1 and a molecular weight of about 400 to 3,000 reacted with:

(B) amine selected from the group consisting of:

(1) monoamine having the formula:

R-NH

' wherein R is alkyl of about 12 to 28 carbons atoms, and (2) polyamine' having the formula:

NH (RNH) --H wherein n is an integer of 2 to 10; R is alkylene of 2 to 7 carbon atoms, and

(C) para-aminophenol:

the mole ratio of (B) to (A) being about 0.1 to

2 moles of (B) per reactive carboxylic acid group per mole of (A) and said reactant (C) being present in an amount of about 0.2 to 2 moles per basic nitrogen per mole of reactant (B). 4. The product of claim 3 wherein said amine is a mixture of octadecylamine and diethylaminopropylamine.

References Cited UNITED STATES PATENTS 3,010,810 11/1961 Stayner et al. 4462 3,444,151 5/1969 VcrdOl et a1. 26086.7

JOSEPH L. SCHOFER, Primary Examiner D J. KIGHT III, Assistant Examiner US. Cl. X.R. 2s2 s1.5, 56 

